Gwynn collected 3,141 hits during a Hall of Fame career spanning 20 seasons with the San Diego Padres.
He fought cancer in a salivary gland and in his cheek, battling the disease over the last four years.
A left-hander, Gwynn had a career .338 batting average, won eight National League batting titles, and played in the franchise’s only two World Series.
He had been signed to a one-year contract extension as the baseball coach at San Diego State on June 11. He had been on medical leave since late March while recovering from cancer treatment. He took over the program at his alma mater after the 2002 season.